This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
DL downlink (eNB towards UE)
eNB EUTRAN Node B (evolved Node B)
EPC evolved packet core
EUTRAN evolved UTRAN (LTE)
CDM code division multiplexing
CQI channel quality indicator
FDD frequency division duplex
FDMA frequency division multiple access
LTE long term evolution
MAC medium access control
MM/MME mobility management/mobility management entity
Node B base station
OFDMA orthogonal frequency division multiple access
O&M operations and maintenance
PDCP packet data convergence protocol
PHY physical layer
PUCCH physical uplink control channel
PUSCH physical uplink shared channel
RLC radio link control
RRC radio resource control
SGW serving gateway
SC-FDMA single carrier, frequency division multiple access
SRS sounding reference signal
SU-MIMO single user multiple input multiple output
TDD time division duplex
TTI transmission timing interval
UE user equipment
UL uplink (UE towards eNB)
UTRAN universal terrestrial radio access network
The specification of a communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as EUTRA) is currently nearing completion within the 3 GPP. As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.6.0 (2008-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety.
FIG. 1 reproduces Figure 4.1 of 3GPP TS 36.300, and shows the overall architecture of the EUTRAN system. The EUTRAN system includes eNBs, providing the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and eNBs.
The eNB hosts the following functions:
functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards Serving Gateway;
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
measurement and measurement reporting configurations for providing mobility and scheduling.
The system described above may be referred to for convenience as LTE Rel-8, or simply as Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.101, 36.211, 36.311, 36.312, etc.) may be seen as describing the entire Rel-8 LTE system.
Of particular interest herein are the further releases of 3GPP LTE targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A).
Reference can also be made to 3GPP TR 36.913, V8.0.0 (2008-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 8), which is incorporated by reference herein in its entirety.
LTE-A will be a radio system fulfilling the ITU-R requirements for IMT-Advanced while maintaining backwards compatibility with LTE Rel-8. It is assumed at present that single user (SU) MIMO UEs having, for example, two, three or four transmission antennas will be part of LTE-A.
Due to the required backwards compatibility, an LTE-A UE must operate in an LTE Rel-8 cell or network. However, LTE Rel-8 supports mainly single antenna UL transmissions, with an option for transmit antenna selection. Thus, one important item related to the specification and design of a LTE-A SU-MIMO UE is the transmission capability of the UE in a LTE Release 8 cell.